Variable force hopper gate actuating mechanism

ABSTRACT

A rack and pinion gear variable force applying mechanism particularly suitable for opening the gates of railway hopper cars. The mechanism includes a cam member, preferably rotatably mounted on the gate, and a rack member preferably fixed to a frame guiding the gate between open and closed positions. Teeth on the cam cooperate with slots on the rack to move the gate between open and closed positions as the cam is rotated through substantially one revolution. Each succeeding tooth on the cam is located a greater radial distance from the center of rotation of the cam than a preceding tooth to transmit a variable force between the cam and rack during cam rotation.

United States Patent [191 Winsor Aug. 6, 1974 VARIABLE FORCE HOPPER-GATE ACTUATING MECHANISM [75] Inventor: Robert Beck Winsor, Senneville,

Quebec, Canada [73] Assignee: lEC-Holden Ltd., Montreal,

Quebec, Canada [58] Field of Search 105/282 R, 282 A, 282 P, 105/305, 308 R; 74/437 [56] References Cited UNlTED STATES PATENTS 1,035,801 8/1912 Meissner 105/305 X 3,387,570 6/1968 Pulcrano et a1. 105/282 P Primary ExaminerM. Henson Wood, Jr. Assistant ExaminerHoward Beltran Attorney, Agent, or Firm-Alan Swabey; Robert Mitchell [57] ABSTRACT A rack and pinion gear variable force applying mechanism particularly suitable for opening the gates of railway hopper cars. The mechanism includes a cam member, preferably rotatably mounted on the gate, and a rack member preferably fixed to a frame guiding the gate between open and closed positions. Teeth on the cam cooperate with slots on the rack to move the gate between open and closed positions as the cam is rotated through substantially one revolution. Each succeeding tooth on the cam is located a greater radial distance from the center of rotation of the cam than a preceding tooth to transmit a variable force between the cam and rack during cam rotation.

11 Claims, 5 Drawing Figures VARIABLE FORCE HOPPER GATE ACTUATING MECHANISM BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a mechanism for transmitting a variable force to a member to be moved.

The invention is more particularly directed to a mechanism for transmitting a variable force to a member to move it between a first position, where it is under a load, and a second position, where it has little or no load, the force varying between a high value with the member at the first position and a low value with the member at the second position substantially in proportion to the load on the member.

2. Description of the Prior Art The invention is particularly directed to a mechanism for use in the opening of gates in the bottom of railway hopper cars. The gates in the hopper cars are used to close outlet openings in the bottom of the hopper car and extend substantially horizontally across the opening. When the hopper car is filled with material, a very high initial force is required to crack open the gate in order to get it moving to an open position so that the hopper car can be emptied through the outlet opening. The high initial force is, in part, due to the fact that a major surface portion of the gate is supporting the ma terial in the hopper thereby causing high friction forces between the material and the gate, and the gate and its supports. Once the door has been cracked open to initiate movement and then continues to move away from the outlet opening, less force is required to keep it moving to its fully open position. The force required reduces substantially in proportion to the reduction in the weight of material carried by the gate as it moves away from the outlet opening. The high initial force applied to open the gate results in a very low initial rate of travel of the gate due to the mechanical advantage required. Once the gate has been cracked open, however, the rate of travel of the gate can be increased in order to quickly move the gate to the fully open position.

Mechanisms for applying a high initial force to the gate in order to crack it open are known. One example of such a mechanism is shown in US. Pat. No. 3,387,570, issued June 1 l, 1968, F. C. Pulcrano and C. E. Becker, inventors. In this patent, a smooth surfaced cam member is used to transmit a high initial force from a crank to the gate to crack it open in order to get it moving. Once the gate his been cracked open, the cam member becomes inoperative, and a gear and rack mechanism, having less mechanical advantage than the cam member, is then used to quickly move the gate to its fully open position upon continued rotation of the crank. This type of mechanism has disadvantages, however. Numerous parts are required to provide, separately, both the high initial force and a high rate of travel after cracking open the gate. Also, several turns of the crank are required to move the door to a fully open position at a high rate of travel through the gear and rack mechanism. In addition, the mechanism makes it difficult to determine if the car is to be unloaded. Often, a gate in a hopper car is opened an inch the gate must be closed. A high positive force must thus be applied to again close the gate, and the mechanism shown in the patent cannot provide this.

SUMMARY OF THE lNVENTlON It is the purpose of the present invention to provide a variable force transmitting mechanism which provides a high initial force to initially open the gate and which force then decreases during movement of the gate while increasing rate of travel of the gate. It is a further purpose to provide a mechanism which needs fewer parts thus making it less expensive to build and service than known devices and which opens the gate more quickly than the known devices. It is another purpose to provide a gate opening mechanism which can apply a high force, near the end of travel of the gate, during closing.

The invention is more particularly directed toward a mechanism for transmitting a force to a member to be moved between first and second positions which includes means for guiding the member between the first and second positions, and at least one cam member rotatably mounted on one of the movable member or the guiding means. A second elongated member is fixedly mounted on the other of said movable member or guiding means. The cam has a working surface substantially equal in length to the distance the movable member moves between the first and second positions. A plurality of first force transmitting elements are provided on the working surface with each succeeding first element, in one direction of rotation of the cam, spaced radially farther from the center of rotation than each preceding element. The second elongated member has an elongate working surface with a plurality of second force transmitting elements thereon. The first and second elements cooperate on rotation of the cam to transmit a variable force to the movable member to move it between the first and second positions.

In the preferred embodiment, the invention is particularly directed toward a variable force transmitting mechanism for use in opening a gate on a railway hopper car. The mechanism includes a frame on the bottom of the hopper of a railway car. The frame includes guide means for guiding a gate between a first position closing an outlet in the hopper, and a second position fully opening the outlet. A cam member is rotatably mounted on one of the gate or frame. An elongated member is mounted on the other of the gate or frame. The cam has a working portion substantially equal in length to the distance the gate moves between the first closed and the second open positions and consisting of a plurality of first force transmitting elements with each first element, in one direction of rotation of the cam, spaced radially farther from the center of rotation than each preceding first element. The elongated member has a working portion consisting of a plurality of second force transmitting elements. The first and second elements cooperate on rotation of the cam, to transmit a variable force to the gate, to move it between the first, closed and the second, open positions.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in detail having reference to the accompanying drawings, wherein:

FIG. 1 is a plan view of the mechanism installed in a railway hopper car; i

FIG. 2 is a side elevation view of the mechanism DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 2 and 3 illustrate the bottom portion of a single hopper 1 in a railway hopper car. The walls 3 of the hopper angle inwardly and define a rectangular opening 5 with their bottom edges 7, as shown in FIG. 1. A frame 9 is mounted on the walls 3 of the hopper at the bottom thereof about the opening 5. The frame 9 includes walls 10 attached to the walls 3 of the hopper car 1 with the lower edges 12 of the walls 10 defining an opening 14. The frame 9 also includes a pair of side members 11 and 13 joined at one end by a first transverse member 15 and a second transverse member 17 joining the side members intermediate their ends. The side, first and second transverse members box in the opening 5. The side members extend past the wall of the hopper and are joined at their other end by a third transverse side member 19. The side members carry suitable means for guiding a gate 21 between closed and open positions relative to the opening 5 of the hopper. A first channel member 23 extends between the side members 11 and 13 just beneath the second transverse member 15 so as to support the gate 21. Projections 24 are located between side members l1, 13 at the one end to support the front of gate 21. Projections 25 are located on the side members 11 and 13 to provide further support for the gate 21. A suitable seal 27 is carried by the frame about the opening and located above the gate to cooperate with the upper surface of the gate in its closed position to seal the opening 5. Channels 29 are carried on the side members 11 and 13 between the second and third transverse members l7, 19 to guide the gate as it moves to its fully open positron.

The gate 21 can have suitable locking means 30, as shown in FIGS. 1 and 5. A latch 32 can be pivotably connected intermediate its ends by a pin 34 to the edge of the gate 21. The latch includes a rear extension 36 extending under and against the gate for maintaining the latch horizontal, and a forward extension 38 having a stop shoulder 40. The stop shoulder 40 cooperates to abut against a stop block 42 carried between two support members 44 mounted between first channel member 23 and the third side member 19 to prevent the gate from moving until the latch 32 is flipped up. The latch 32 can have an aperture 46 therethrough, which, with the latch in the abutting position, is aligned with apertures 48 in support members 44 to receive a common seal tape 50 to lock the gate in a closed position. The rear extension 36 of the latch 32, when latch 32 is open in the vertical position, will contact stop block 42 as the gate 21 moves to the open position causing the latch 32 to fall to the horizontal position again. Then, when the gate is closed, the latch 32 rides back over stop block 42 and falls automatically back into a locking position behind stop block 42.

A variable force transmitting mechanism 31 is provided to move the gate between its fully closed position, as shown in FIG. 2, to its fully open position, as shown in FIG. 3. The mechanism 31 includes a pair of identical cams 33 fixedly mounted on a shaft 35 which in turn is rotatably mounted on one end of the gate adjacent the opening 5'with the gate in a closed position. The shaft 35 is rotatably carried in shaft supports 37 mounted on the upper surface of the gate. One end 39 of the shaft is formed to receive a crank (not shown) for rotating the shaft, and the cams fixed thereto.

Each cam 33 has a peripheral working surface 41 which has a length substantially equal to the distance the gate must move between its closed and fully open positions. The surface 41 extends substantially 360 about the center of rotation of the cams. A series of substantially equally, spaced-apart, generally radially projecting teeth 43 are provided on the cam surface 41. The surface 41 is shaped so as to have each succeeding tooth, in the direction of rotation of the cam on opening the gate, located a greater radial distance from the center of rotation of the cam than the preceding tooth.

Each cam 33 cooperates with a rack member 45 mounted on the side members ll, 13 of the frame. The rack members 45 have a length substantially equal to the distance the gate moves between open and closed positions and extend at an angle diverging away from the direction of movement of the gate. The rackmembers 45 are fixed to the frame to extend at an angle such that the working surface 41 of the cams tracks along the surface 49 of the rack members as the cams are rotated and the gate moves horizontally from its fully closed to its fully open position, while the cam surface 33 maintains contact with the tracking surface 49. The rack members have equally spaced slots 47 in their tracking surface 49 for cooperating with the teeth 43 on the cams. The spacing between adjacent slots and adjacent teeth is chosen so that there is always at least one tooth cooperating with a respective slot in order to maintain a positive drive at all times between the gate and the frame as the gate moves relative to the frame.

The cams 33 and rack members 45 are mounted on the gate and frame respectively so that with the gate in the fully closed position, the first tooth 43a on the cams, extending the shortest radial distance Ra from the center of rotation of the cams, is located in the first slot 47a on the racks adjacent the opening. To open the gate, the shaft 35 is rotated by a crank through substantially 360 to thereby rotate the earns 33 through substantially 360. As the cams are rotated, force is transmitted through the first tooth 43a to the rack members through the first slot 47a. This initial force is a high force since the moment arm Ra through which it is transmitted is relatively short. This high force cracks the gate open, moving it in a direction away from the opening guided by members 27. As the gate moves, the cams continue their rotation through the crank, and the next adjacent tooth 43b moves into its respective slot 47b just before the first tooth 43 0 moves clear of its slot 47a. Tooth 43b has a slightly longer moment arm Rb than tooth 43a so that less force is transmitted to the gate than by the first tooth 43a.,I-Iowever, less force is now required to continue movement of the gate. Upon continued rotation of the crank through substantially 360, each succeeding tooth 43c, 43d, etc., cooperates with its respective slot 47c, 47d, etc., in the rack members to move the gate with decreasing force and at an increasing rate, assuming substantially constant force applied through the crank, to its fully open position. The teeth 43 are shaped to move readily into and out of the slots 47, as shown in FIG. 4.

Preferably, the cams 33 can be formed to provide a working surface 41 which extends somewhat greater than 360 about the center of rotation of the cams. Since each succeeding tooth, in the direction of rotation to open the gate, extends a greater radial distance from the center of rotation than the preceding tooth, the last few teeth 43x, 43y, etc., are located a considerable distance from the center of rotation compared to the first few teeth 43a, 43b, etc., after having traversed substantially 360 about the cam. The cams can, therefore, be formed to have a tail portion 51 which is formed to overhang an initial portion 53 of the working surface 41, as shown in FIG. 4, to thereby have the end portion 55 of the working surface overlap the initial portion 53. The degree of overlap is dependent upon the force to be transmitted by the cams and the strength of the tail portion of the cams.

While one specific embodiment of the invention has been described, it will be obvious that other embodiments can be employed as well. For example, the teeth 43 can be carried on the rack members instead of on the cams, and the cams can be provided with the slots 47 on their working surfaces.

While two cams and racks have been used in the particular hopper car mechanism described, a single cam and rack could be used in other force transmitting applications.

The cam or cams, having either the teeth or the slots on their working surfaces, could be mounted for rotation in a fixed position on the frame, and the rack members could be fixedly mounted to the gate.

While the working surfaces of the rack members have been shown as being straight, in order to provide a linear tracking surface following a linear path generated by the teeth of the cam on its rotation during gate movement, the surfaces could be curved as well.

I claim:

1. A variable force transmitting mechanism for moving a gate member between a first and a second position with a variable force, including means for guiding the member for movement between the first and second positions, a cam rotatably mounted on one of the gate member or the guide means, a second elongate member fixedly mounted on the other of the member or the guide means, said cam having a first working surface substantially equal in length to the distance the member moves between the first and second positions, a plurality of first, force transmitting elements on the working surface extending substantially about the center of rotation of the cam with each succeeding element, in one direction of rotation of the cam, spaced radially farther from the center of rotation than each preceding element, said second elongate member having a second working surface with a plurality of second, force transmitting elements thereon, said first and second elements cooperating, on rotation of the cam, to transmit a variable force to the member to move it between the first and second positions,

said elongate member extending at an angle relative to said means for guiding the gate member such that the distance between corresponding points on the guiding means and the elongate member varies as the distance between the working surface and the center of rotation of the cam.

2. A mechanism as claimed in claim 1, wherein the first working surface extends substantially 360 about the center of rotation of the cam.

3. A mechanism as claimed in claim 1, wherein the elongate member is mounted to extend at an angle with respect to the direction of movement of the movable member along the guiding means.

4. A mechanism as claimed in claim 1, wherein the first elements comprise a plurality of teeth equally spaced about the working surface of the cam, and the second elements comprise a plurality of equally spaced slots, each tooth cooperating with a respective slot.

5. A mechanism as claimed in claim 1, wherein the cam is formed to have a tail portion overhanging a portion of the cam working surface, the tail portion also carrying a portion of the cam working surface.

6. A mechanism as claimed in claim 1, including means for mounting the cam on the movable member and means for rotating the cam through substantially 360 during movement of the member between the first and second positions.

7. A variable force transmitting mechanism for use in moving a gate in a railway hopper car comprising a frame on the hopper car, guide means on the frame for guiding the gate between a first position closing an outlet in the car and a second position fully opening the outlet, a cam rotatably mounted on one of the gate or frame, an elongate member on the other of the gate or frame, the cam having a working portion substantially equal in length to the distance the gate moves between the two positions and consisting of a plurality of first, force transmitting elements with each first element, in one direction of rotation of the cam, spaced radially farther from the center of rotation of the cam than each preceding element, the elongated member having a working portion consisting of a plurality of second, force transmitting elements, the first and second elements cooperating on rotation of the cam, to transmit a variable force to the gate to move it between the closed and fully open positions,

said elongate member extending at an angle relative to said guide means such that the distance between corresponding points on the guide means and the elongate member varies as the distance between the working surface and the center of rotation of the cam.

8. A mechanism as claimed in claim 7, wherein the working portion of the cam extends substantially through 360 at the center of rotation of the cam.

9. A mechanism as claimed in claim 8, wherein the cam is mounted on the gate and the elongate member on the frame.

10. A mechanism as claimed in claim 9, wherein the first elements comprise equally spaced apart teeth and the second elements comprise equally spaced apart slots.

11. A mechanism as claimed in claim 7, including cooperating locking means mounted on the gate and the frame means for locking the gate in a closed position. 

1. A variable force transmitting mechanism for moving a gate member between a first and a second position with a variable force, including means for guiding the member for movement between the first and second positions, a cam rotatably mounted on one of the gate member or the guide means, a second elongate member fixedly mounted on the other of the member or the guide means, said cam having a first working surface substantially equal in length to the distance the member moves between the first and second positions, a plurality of first, force transmitting elements on the working surface extending substantially about the center of rotation of the cam with each succeeding element, in one direction of rotation of the cam, spaced radially farther from the center of rotation than each preceding element, said second elongate member having a second working surface with a plurality of second, force transmitting elements thereon, said first and second elements cooperating, on rotation of the cam, to transmit a variable force to the member to move it between the first and second positions, said elongate member extending at an angle relative to said means for guiding the gate member such that the distance between corresponding points on the guiding means and the elongate member varies as the distance between the working surface and the center of rotation of the cam.
 2. A mechanism as claimed in claim 1, wherein the first working surface extends substantially 360* about the center of rotation of the cam.
 3. A mechanism as claimed in claim 1, wherein the elongate member is mounted to extend at an angle with respect to the direction of movement of the movable member along the guiding means.
 4. A mechanism as claimed in claim 1, wherein the first elements comprise a plurality of teeth equally spaced about the working surface of the cam, and the second elements comprise a plurality of equally spaced slots, each tooth cooperating with a respective slot.
 5. A mechanism as claimed in claim 1, wherein the cam is formed to have a tail portion overhanging a portion of the cam working surface, the tail portion also carrying a portion of the cam working surface.
 6. A mechanism as claimed in claim 1, including means for mounting the cam on the movable member and means for rotating the cam through substantially 360* during movement of the member between the first and second positions.
 7. A variable force transmitting mechanism for use in moving a gate in a railway hopper car comprising a frame on the hopper car, guide means on the frame for guiding the gate between a first position closing an outlet in the car and a second position fully opening the outlet, a cam rotatably mounted on one of the gate or frame, an elongate member on the other of the gate or frame, the cam having a working portion substantially equal in length to the distance the gate moves between the two positions and consisting of a plurality Of first, force transmitting elements with each first element, in one direction of rotation of the cam, spaced radially farther from the center of rotation of the cam than each preceding element, the elongated member having a working portion consisting of a plurality of second, force transmitting elements, the first and second elements cooperating on rotation of the cam, to transmit a variable force to the gate to move it between the closed and fully open positions, said elongate member extending at an angle relative to said guide means such that the distance between corresponding points on the guide means and the elongate member varies as the distance between the working surface and the center of rotation of the cam.
 8. A mechanism as claimed in claim 7, wherein the working portion of the cam extends substantially through 360* at the center of rotation of the cam.
 9. A mechanism as claimed in claim 8, wherein the cam is mounted on the gate and the elongate member on the frame.
 10. A mechanism as claimed in claim 9, wherein the first elements comprise equally spaced apart teeth and the second elements comprise equally spaced apart slots.
 11. A mechanism as claimed in claim 7, including cooperating locking means mounted on the gate and the frame means for locking the gate in a closed position. 